Para-phenyl stilbene derivatives

ABSTRACT

Stilbene derivatives having at least one further phenyl substituent in the para-position to a benzene ring in the stilbene are optical brighteners particularly suitable for incorporation on spinning masses.

This is a division of application Ser. No. 596,287, filed July 16, 1975,now U.S. Pat. No. 4,032,558, which in turn is a continuation, ofapplication Ser. No. 316,448, filed Dec. 19, 1972, now abandoned.

This invention concerns new stilbene derivatives.

The invention provides compounds of formula I, ##STR1## in which R₁ andR₅ each signifies hydrogen, nitrile, or linear alkyl of 1 to 4 carbonatoms,

R₂, R₄, R₆ and R₈ each signifies hydrogen, one of the followingfirst-order substituents: halogen, alkyl or alkoxy of 1 to 8 carbonatoms, alkenyl of 3 to 8 carbon atoms, or one of the followingsecond-order substituents: --CN, --COOR', --CONR'R", --SO₃ R"', --SO₂NR'R" or SO₂ R"",

in which R' signifies hydrogen, alkyl of 1 to 22 carbon atoms,hydroxyalkyl of 2 to 4 carbon atoms, phenyl or methyl- orchlorine-substituted phenyl,

R" signifies hydrogen, alkyl of 1 to 8 carbon atoms or hydroxylalkyl of2 to 4 carbon atoms, or

R' and R" together with the vicinal nitrogen atom form a pyrrolidine,piperidine, piperazine or morpholine ring,

R"' signifies phenyl or methyl- or chlorine-substituted phenyl,

R"" signifies alkyl of 1 to 4 carbon atoms, phenyl or methyl- orchlorine-substituted phenyl,

R₃ and R₇ each signifies hydrogen, a first-order or second-ordersubstituent as defined above or a heterocycle of formula, ##STR2## inwhich X signifies --O--, --S--, --NH-- or --NR""'-,

R""' signifies alkyl of 1 to 4 carbon atoms or hydroxyalkyl of 2 to 4carbon atoms,

A₁ and A₂ each signifies, if X signifies --O--, phenyl or phenylsubstituted by chlorine or alkyl or alkoxy of 1 to 4 carbon atoms, or ifX signifies --O--, --S--, --NH-- or --NR""', they together form theatoms of a condensed naphthalene nucleus, a condensed benzene ring or acondensed benzene ring substituted by fluorine, chlorine, nitrile, alkylof 1 to 8 carbon atoms and/or alkoxy of 1 to 8 carbon atoms, and

A₃ signifies phenyl or phenyl substituted by one of the namedfirst-order substituents or by a second-order substituent which does notcontain a heterocyclic radical,

A₄ signifies hydrogen or methyl

p signifies an integer from 1 to 3 and

q signifies an integer from 1 to 3, provided that the total of p and qis at least 3,

the total of p and q and the number of second-order substituents in themolecule is at least 5, the heterocycle significances (a), (b) and (c)for R₃ and R₇ and the --CN significance for R₁ or R₅ being considered assecond-order substituents,

and if one of the substituents R₃ and R₇ is a heterocycle (a), (b) or(c), either the total of p and q is at least 4 and/or at least twofurther non-heterocyclic second-order substituents are present in themolecule.

The alkyl radicals (first-order substituents) occurring in the compoundsof formula I may be, for example, methyl, ethyl, n-propyl, iso-propyl,n-butyl, iso-butyl, tert. butyl, n-amyl, tert. amyl, iso-amyl, sec.amyl, n-hexyl, n-octyl, iso-octyl and 2-ethylhexyl. Only linear radicalswith 1 to 4 carbon atoms are suitable as alkyl radicals R₁ and R₅, i.e.methyl, ethyl, n-propyl and n-butyl. Generally the lower radicalscontaining 1 to 4 carbon atoms are preferred, while methyl is preferredas the significance of R₁ and R₅.

The following may be named as examples of alkenyl and alkoxy first-ordersubstituents: allyl, 1-, 2- and 3-butenyl, 1-hexenyl, methoxy, ethoxy,n-propoxy, n-butoxy, tert. butoxy, n-hexyloxy and 2-ethylhexyloxy, ofwhich alkoxy radicals containing 1 to 4 carbon atoms, in particularmethoxy, are preferred.

The halogen atoms in the compounds of formula I may be fluorine orpreferably chlorine atoms, while as reactive halogen atoms in theintermediates described hereinafter, chlorine, bromine and possiblyiodine atoms are of prime interest.

As examples of "non-heterocyclic" second-order substituents, i.e.second-order substituents with the exception of the heterocycles (a),(b) and (c), the following may be named: the nitrile group, the carboxylgroup, carboxylic acid alkyl ester in which the alkyl radical contains 1to 22 or preferably 1 to 8 carbon atoms, e.g. carboxylic acid methyl,ethyl, propyl, isopropyl, butyl, amyl, hexyl, iso-octyl, n-decyl,n-dodecyl, cetyl, stearylester groups, carboxylic acid β-hydroxyethyl,β-hydroxypropyl, phenyl, p-chlorophenyl, p-methylphenyl,2,4-dimethylphenyl and 2,5-dichlorophenylester groups, sulphonic acidphenyl, p-chlorophenyl, 2,5-dichlorophenyl, p-methylphenyl and2,4-dimethylphenylester groups, methyl, ethyl, n-propyl, iso-propyl,n-butyl, iso-butyl, tert. butyl, phenyl, p-chlorophenyl, p-methylphenyl, 2,4-dimethylphenyl and 2,4,6-trimethylphenylsulphone groups, thefree carboxylic and sulphonic acid amide groups and carboxylic acid andsulphonic acid amide groups derived, for example, from the followingamines: methyl, ethyl, propyl, butyl, tert. butyl, amyl, iso-amyl,hexyl, octyl, lauryl, dimethyl, diethyl, ethanol-amine anddiethanol-amine, N-methyl-N-ethylamine, N-methyl-N-propylamine, aniline,toluidine, xylidine, p-chloroaniline, N-methylaniline, pyrrolidine,piperidine, piperazine and morpholine.

Of the aforenamed second-order substituents, the following arepreferred: --CN, the alkylsulphone groups, --SO₂ --C₆ H₅, --SO₃ --C₆ H₅,--CONH₂, --CO--NHCH₃, --CO--N(CH₃)₂, --CO--N(C₂ H₅)₂, --CO--N(CH₂ CH₂OH)₂, --CO--NH--CH₂ CH₂ OH, the carboxylic acid alkylester groups(preferably carboxylic acid alkyl (1-4 ester groups), --SO₂ NH₂, --SO₂NHCH₃, --SO₂ N(CH₃)₂ and --SO₂ NHC₆ H₅.

In addition to the stated substituents, the heterocyclic substituents offormulae (a), (b) and (c) are suitable as substituents R₃ and R₇. In theradical of formula (a), X signifies sulphur, alkylimino orhydroxyalkyl-imino, where alkyl contains 1 to 4 carbon atoms andhydroxyalkyl contains 2 to 4 carbon atoms (e.g. methyl, ethyl, n-propyl,iso-propyl, n-butyl, tert. butyl, β-hydroxyethyl orβ-hydroxypropylimino) or, preferably, oxygen. If X signifies oxygen, A₁and A₂ may each have, for example, one of the following meanings:phenyl, 4-methyl-, 2,4-dimethyl-, 3,4-dimethyl-, 4-ethyl-, 4-butyl-,4-methoxy-, 4-ethoxy- or 3-methyl-4-methoxyphenyl. If A₁ and A₂ formjointly a condensed ring, this may be an unsubstituted naphthalene ringor a benzene ring which may bear, preferably in one or optionally ineach of the 5 and 6 positions of the benzoxazole ring, preferably one ofthe following substituents: methyl, ethyl, n-propyl, n-butyl, methoxy,ethoxy, n-butoxy, tert. butoxy, chlorine or --CN.

As radical A₃ unsubstituted phenyl or phenyl substituted by any of theaforenamed first-order substituents or non-heterocyclic second-ordersubstituents is suitable. A₃ signifies preferably phenyl orp-chlorophenyl.

The total of p and q may be 3 to 6, but compounds of formula I in whichthe total of p and q is 4, 5 or 6 are preferred.

The following compounds are especially preferred in view of theirproperties as optical brightening agents.

Compounds of formula XVI, ##STR3## in which p and q are as definedabove,

R₁₁ and R₁₅ each signifies hydrogen, methyl or --CN, preferably hydrogenor --CN,

R₁₃ and R₁₇ each signifies hydrogen or a non-heterocyclic second-ordersubstituent, preferably --CN, an alkyl- or phenyl-sulphone group or acarboxylic acid amide or ester group,

R₁₂, R₁₄, R₁₆ and R₁₈ each signifies a first-order substituent orpreferably hydrogen,

and where the molecule contains 2 to 4 second-order substituents.

Compounds of formula XVII, ##STR4## where R₂₁ and R₂₅ each signifieshydrogen, methyl or cyano, preferably hydrogen or cyano,

R₂₂, R₂₄, R₂₆ and R₂₈ each signifies hydrogen or a first-ordersubstituent, preferably hydrogen,

R₂₃ and R₂₇ each signifies one of the heterocyclic second-ordersubstituents of formulae (a), (b) or (c),

r signifies an integer from 1 to 3, preferably 1 or 2,

s signifies an integer from 1 to 3, preferably 1 or 2, and the total ofr and s is 3 or 4.

Compounds of formula XVIII, ##STR5## in which R₃₁ and R₃₅ each signifieshydrogen, --CN or methyl, preferably --CN or methyl,

R₃₂, R₃₄, R₃₆ and R₃₈ each signifies hydrogen or a first-ordersubstituent, preferably hydrogen,

one of the symbols R₃₃ and R₃₇ signifies one of the heterocycles (a),(b) or (c),

the other symbol R₃₃ or R₃₇ signifies hydrogen, a first-ordersubstituent or a non-heterocyclic second-order substituent,

t signifies an integer from 1 to 3,

u signifies an integer from 1 to 3, the total of t and u is 3, 4 or 5,

and where at least one of the substituents R₃₁, R₃₅ and R₃₃ or R₃₇ is anon-heterocyclic second-order substituent and, if the total of t and uis 3, at least two of the substituents R₃₁, R₃₅ and R₃₃ or R₃₇ arenon-heterocyclic second-order substituents.

The essential feature of the compounds of formula I, above all withrespect to their properties as optical brightening agents, is thecombination between the basic structure and the second-ordersubstituents and their position in the molecule. The compounds withgenerally the best properties are those in which one, two, three or allfour of the substituents R₁, R₃, R₅ and R₇ are second-ordersubstituents. The first-order substituents have no appreciable effect onthe optical brightening properties, although they may, for example,affect the solubility in organic polymers. Even when second-ordersubstituents are present in the molecule as substituents R₂, R₄, R₆ andR₈, they have no significant effect, compared with the second-ordersubstituents R₁, R₃, R₅ and R₇, on the fluorescence of the brightener orconsequently the fluorescence of the optically brightened substrate.Therefore, compounds of formula I in which R₂, R₄, R₆ and R₈ signifyhydrogen are generally preferred to those in which R₂, R₄, R₆ and R₈have a significance other than hydrogen.

The invention also provides a process for the production of compounds offormula I, which comprises (a) reacting a compound of formula II,##STR6## in which R₁ to R₄ and p are as defined above, and

Y signifies --CHO or a functional derivative thereof or --CO--COOH,

with a compound of formula III, ##STR7## in which R₅ to R₈ and q are asdefined above, and

Z signifies a substituent which activates the vicinal methylene group,or hydrogen if Y is an anile derivative of the aldehyde group and noequally active or more active methyl is present,

and if a substituent Z with a significance other than hydrogen remainsin the reaction product, replacing this with hydrogen,

(b) cleavage of two of the substituents Y₁ and Z₁, with simultaneousreduction or oxidation if necessary, of compounds of formula IV,##STR8## in which R₁ to R₈, p and q are as defined above,

each Y₁ and each Z₁ independently signifies hydrogen, halogen, ahydroxyl or acyloxy group or (Y₁)₂ and/or (Z₁)₂ each signifies an oxogroup,

and if the substituents Y₁ and/or Z₁ have a significance other thanhydrogen in the reaction product, replacement of such substituent byhydrogen, or

(c) replacing a halogen atom in a compound of formula V, ##STR9## inwhich p and q are as defined above, and

at least one of the symbols R₁ ' to R₈ ' signifies halogen and theremaining symbols have the same significance as R₁ to R₈ as definedabove,

to produce a corresponding compound of formula I in which at least oneof R₁ to R₈ is nitrile,

(d) converting a compound of formula I in which at least one of thesubstituents R₂, R₃, R₄, R₆, R₇ and R₈ signifies -CN by conversion ofthe -CN group into a compound of formula I having a correspondingcarboxylic acid amide, carboxylic acid ester or free carboxylic acidgroup,

(e) converting a compound of formula I in which at least one of thesubstituents R₃ and R₇ signifies a carboxylic acid, carboxylic acidester or carboxylic acid amide group, into a compound of formula Ihaving a corresponding heterocycle (a) substituent, if necessary afterraction to the corresponding carboxylic acid halide group,

(f) reacting in alkaline medium and/or under oxidative conditions, acompound of formula VI, ##STR10## in which R₁ to R₄ and p are as definedabove, and

W signifies hydrogen, halogen or -P.sup.⊕ (aryl)₃ anion.sup.⊖,

for which reaction the medium must be alkaline if W signifies halogenand must be carried out in the presence of an oxidizing agent if Wsignifies hydrogen and must be carried out in the presence of a protonacceptor and an oxidizing agent if W signifies [P(aryl)₃ ].sup.⊕anion.sup.⊖, to form a compound of formula I in which R₅, R₆, R₇, R₈ andq are identical to R₁, R₂, R₃, R₄ and q in the compound of formula VI,or

(g) by thermal treatment to split off CO₂ or N₂ groups in an inert gasatmosphere of compounds of formulae VII or VIII, respectively, ##STR11##in which R₁ to R₈, p and q are as defined above, to split off the CO₂ orN₂ respectively.

Process variant (a) may be carried out in accordance with conventionalmethods, for example in the absence of air and preferably in thepresence of a suitable catalyst, for example boric acid, zinc chloride,arylsulphonic acids, alkali metal and alkaline-earth salts ofarylsulphonamides, acetic anhydride, alkali acetates, piperidine, alkalimetal and alkaline-earth hydroxides, alkali metal and alkaline-earthalcoholates, suitably at temperatures of 0° to 200° C., preferably at20° to 160° C.

In the compounds of formula II, Y signifies the group -CO-COOH or thegroup -CHO or a functional derivative of the aldehyde group suitable forthe reaction, e.g. an anile, a hydrazone, an oxime or an azine. In thecompounds of formula III, Z signifies hydrogen or a radical whichactivates the CH₂ group so that it can be reacted with the aldehyde oraldehyde derivative or with the ketocarboxylic acid group. Examples ofsuch activating groups are the carboxyl group, a carboxylic acid esteror amide group, optionally the cyano group, and advantageously one ofthe groups ##STR12## or -[P(aryl)₃ ].sup.⊕ anion.sup.⊖, where alkyl ispreferably lower, e.g. with 1 to 6 carbon atoms, and is optionallysubstituted, e.g. by methoxy, ethoxy, phenyl or phenoxy, and includescycloalkyl, e.g. cyclohexyl, and aryl is preferably mono-nuclear(optionally substituted phenyl) and anion.sup.⊖ is an equivalent of anysuitable anion, preferably of a mineral acid, e.g. Cl.sup.⊖ or Br.sup.⊖.

The reaction can be carried out, for example, by melting the reactants,but it is preferred to use an inert organic solvent, e.g. aliphatic oraromatic, preferably halogenated, hydrocarbons, alcohols, ethers,glycols, formamide, dimethyl acetamide, N-methyl pyrrolidone,acetonitrile, dimethyl sulphoxide, tetramethylene sulphone or hexamethylphosphoric triamide. For the reaction of compounds containing phosphorus(the Wittig and related reactions), see, e.g., "Organo-PhosphorusCompounds", International Symposium, Heidelberg 1964, ButterworthsScientific Publications. If a radical Z different from hydrogen ispresent in the reaction product, it is replaced by hydrogen by asuitable method in conventional manner.

Process variant (b) may be carried out in accordance with theconventional methods; for example compounds in which all the Y₁ and Z₁radicals are hydrogen can be dehydrated to the corresponding stilbenecompounds in analogy with the process described in the published GermanPatent Application 1,670,398, for example as described below. If one ormore of the symbols Y₁ and Z₁ signifies halogen, preferably chlorine orbromine, and one or more of the remaining symbols Y₁ and Z₁ signifyhydrogen, dehydrohalogenation may be carried out in known manner,preferably with heating, suitably at 100° to 300° C., or in particular150° to 200° C., preferably in the presence of alcohols or glycols ofhigh boiling point (ethylene glycol, propylene glycol) and/or strongbases (alkali, alcoholates); dehalogenation may be carried out inaccordance with the known methods, for example with metals, e.g. zinc,or with copper (I) compounds or with triaryl phosphines in polarsolvents, e.g. dimethyl formamide, dimethyl sulphoxide, N-methylpyrrolidone etc., with heating, preferably at the refluxing temperature.With a dehydrohalogenation reaction, splitting off of acyl-OH may takeplace; acyl-OH signifies preferably a lower acid which splits offreadily, e.g. benzoic acid or preferably acetic acid. Compounds in whichtwo oxygen atoms are present in the bridge member --C(Y₁)₂ --C(Z₁)₂ --,optionally in addition to hydrogen, preferably benzoine compounds, canbe reduced directly to the corresponding stilbene compounds, e.g. withzinc amalgam and an H₂ /HCl current in boiling alcohol (cf. Baroni, C.A.55, 1520e and J. Prakt. Chemie, 4th series, Vol. 20 (1963), pp. 56-61).Although this reaction is also suitable for the production ofasymmetrical compounds, it is preferred to produce symmetrical compoundsof formula I in this way, since, as is known, benzoine compounds, forexample, can be produced from the corresponding aldehydes.

In process variant (c), the exchange of a halogen, preferably a bromine,atom by a nitrile group in the compounds of formula V may be carried outin known manner, for example by reaction in a suitable polar organicsolvent, e.g. one of the aforenamed solvents, quinoline, quinaldineand/or alkylpyridines, e.g. lutidine, with a suitable cyanide,preferably CuCN, optionally in mixture with alkali or alkaline-earthcyanides.

In process variant (d), the conversion of a nitrile group into acorresponding carboxylic acid, carboxylic acid amide or carboxylic acidester group is a conventional reaction and, for example, the acid groupcan be formed in the presence of water and/or alcohol and alkali ormineral acid with heating.

In process variant (e), the reaction of a carboxylic acid ester orhalide group (R₃ and/or R₇) to an X-azole ring of formula (a) may becarried out in conventional manner, e.g. by reaction with a compound offormula XIX, ##STR13## where preferably A₁ and A₂ together form theatoms of an aromatic ring.

If the final product of formula I is to contain heterocyclicsubstituents R₃ and/or R₇, it is preferable to start from compoundswhich themselves contain such heterocycles.

In process variant (f), the reaction of compounds of formula VI may becarried out in accordance with conventional methods, for example asdescribed in the following. If W signifies hydrogen, the reaction iscarried out in the presence of an oxidizing agent, in particular oxygenor sulphur. If oxygen is used, the reaction can be carried out inanalogy with the procedure described in the published German PatentApplication 1,670,398 in a neutral to basic polar solvent, preferably adialkylated acylamide, in particular dimethyl formamide, diethylformamide, dimethyl acetamide or hexamethyl phosphoric acid triamide, inwhich case it is of advantage to work in the presence of a stronglybasic alkali metal compound, preferably an alkali hydroxide, alcoholateor amide and, optionally, with oxygen in mixture with inert gases, e.g.in the form of air, and preferably at temperatures between 10° and 150°C., preferably between 30° and 100° C. When this procedure is employedit is necessary for the starting material of formula VI to be free fromatoms replaceable by alkali metal. When sulphur is used as oxidizingagent, it is advantageous to react at temperatures between 250° and 350°C., preferably between 200° and 300° C., in the absence of solvents; thestoichiometric amount or an excess of sulphur can be used.

The reaction of the compounds of formula VI in which W signifies ahalogen atom, preferably a chlorine or bromine atom, is carried out withstrong bases, e.g. alkali and/or alkaline-earth hydroxide, alcoholate oramide, in particular potassium hydroxide, potassium tert. butylate orNaNH₂, in a polar solvent, for example dimethyl formamide, dimethylacetamide, dimethyl sulphoxide, alcohol etc., with heating, for examplebetween 60° and 200° C. depending on the solvent, preferably at therefluxing temperature.

A modification of the foregoing oxidation process with oxygen or sulphurconsists in employing, in place of compounds of formula VI in which Wsignifies hydrogen, compounds in which W signifies -P.sup.⊕ (aryl)₃anion.sup.⊖ where aryl is preferably mononuclear (optionally substitutedphenyl) and anion.sup.⊖ has the aforesaid significance, and proceeding,e.g. in analogy with the process described in Chem. Ber. 103, 2995-2997(1970). A further mode of operation consists in employing a compound offormula VI in which W signifies -P.sup.⊕ (aryl)₃ anion.sup.⊖ and atleast one of the anions has oxidizing properties and is used asoxidizing agent. Preferably periodates are used. The reaction can becarried out, for example, in analogy with the method described in thepublished German Patent Application 1,925,255 using anhydrous bases, inparticular alkali metal or alkaline-earth alcoholates in dry alcohol,with heating, preferably at the refluxing temperature.

In process variant (g), the pyrolytic reactions of fumaric acid estersof formula VII and the aldazines of formulae VIII may be carried out inaccordance with conventional methods, in particular under an inert gasatmosphere, optionally in the presence of a solvent of high boilingpoint, e.g. Dowtherm or solvent naphtha, and advantageously attemperatures between 200° and 400° C., preferably at about 250° C.

The intermediates of formula V can be produced by known methods, forexample in analogy with the aforedescribed methods for the production ofcompounds of formula I, by the reaction of compounds of formula IX,##STR14## with compounds of formula ##STR15## in which R₁ ' to R₈ ', pand q are as defined above,

in analogous manner to process (a) above, or by the reaction ofcompounds of formula XI, ##STR16## in which R₁ ' to R₈ ', p, q, Y₁ andZ₁ are as defined above,

in analogous manner to process (b) above,

or (for symmetrical compounds of formula V) by the reaction of acompound of formula XII, ##STR17##

in which R₁ ' to R₄ ', p and W are as defined above, in analogous mannerto process (f) above,

or by thermal treatment in analogous manner to process (g) above, ofcompounds of formula XIII or XIV, ##STR18## in which R₁ ' to R₈ ', p andq are as defined above. Intermediates of formula V can also be producedby the reaction of compounds of formula XV, ##STR19## with ahalogenacetaldehyde or a functional derivative thereof, with subsequentdehydrohalogenation and rearrangement of the reaction product. Thisreaction, preferably using compounds in which R₃ ' is different fromhydrogen, with halogenacetaldehyde, may be carried out in accordancewith conventional methods, for example as given above for compounds offormula XI.

The compounds of formulae IV and XI in which at least one of thesubstituents Y₁ and Z₁ signifies halogen, preferably bromine, can beproduced in analogy with the known methods, cf. for example J. Chem.Soc. 1943, 1-4.

The starting compounds of formulae II, III, VI, IX, X, XII and XV can beproduced by known methods or in analogy with the known methods. Thecompounds of formulae IV, VII, VIII, XI, XIII and XIV can be produced inanalogy with the known methods, e.g. by the reaction of hydrazine withthe corresponding aldehydes to compounds of formula VIII or XIV, or byreaction of fumaric acid or a suitable derivative of this acid with thecorresponding phenols to compounds of formula VII or XIII, or as givenabove for the compounds of formulae IV and XI.

The compounds of formula I produced as described above can be purifiedby precipitation from solution in an organic solvent, optionally withthe addition of decolourizing carbon or bleaching earth. They havegenerally relatively little self-colour and are usually of lowsolubility in water. In organic solvents such as chlorobenzene,ortho-dichlorobenzene, dimethyl formamide, acetamide and 2-ethoxyethanolthey dissolve with intense violet to blue fluorescence.

The compounds of formula I exhibit properties as optical brighteningagents and are indicated for the optical brightening of a wide varietyof textile and non-textile substrates, particularly of natural andsynthetic organic polymers. Natural organic polymers include inparticular fibres such as cotton, linen, wool and silk. Syntheticpolymers, in particular fibre-forming polymers, are, for example,polyesters, polyamides, polyurethanes, polyolefins (polyethylene,polypropylene, modified polypropylene), polyvinyl acetate, polyvinylchloride, polyvinylidene chloride, polyacrylonitrile, modifiedpolyacrylonitrile, polystyrene, cellulose diacetate and cellulosetriacetate.

The compounds of formula I can be applied as optical brighteners by anyof the normal methods, for example in the form of solutions, assuspensions in organic solvents or as aqueous dispersions. They can beincorporated with good success in spinning melts and moulding materials,or in the monomers or prepolymers prior to the synthesis of the finalpolymer. The compounds of formula I are especially indicated foraddition to polyester melts to brighten the spun filament. The amount ofdisclosed optical brightener used may vary from, e.g. 0.001 to 0.5% orpreferably from 0.01 to 0.2% by weight relative to the substrate,depending on the method of application and the actual substrate. Thecompounds of formula I may be employed alone or in combination withother brighteners and in the presence of finishing agents, e.g.softeners, antistatic agents, surface-active agents, e.g. detergents,carriers and chemical bleaching agents.

In the following Examples, the parts and percentages, unless otherwisestated, are by weight; the parts by volume relate to the parts by weightas millilitres to grams. The temperatures are given in degreescentigrade. The melting points are uncorrected.

Example 1

Production of the compound of formula 1, ##STR20##

Method α

174.4 Parts of the compound of formula 2, ##STR21## and 72.6 parts ofcopper (I) cyanide are added to 100 parts by volume of dimethylformamide and reacted for 4 hours with stirring and reflux. The mixtureis run with stirring into a solution of 283 parts of iron (III) chloridein 71 parts by volume of concentrated hydrochloric acid and 425 parts ofwater. Stirring is continued for 20 minutes at 60°-70°, then thesuspension is cooled and the precipitate isolated by filtration withsuction, washed with water and dried. After recrystallization fromdilute methanol the compound of formula 3, ##STR22## melting point110°-111°, is obtained in good yield.

A mixture of 97.5 parts of the compound of formula 3, 90 parts ofN-bromosuccinic imide and 1.1 parts of benzoyl peroxide in 505 parts byvolume of carbon tetrachloride is reacted for 18 hours with stirring andreflux. The reaction mixture is cooled and the precipitate filtered withsuction. The filtrate is strongly concentrated by evaporation undervacuum and cooled. The precipitated product is filtered with suction,washed with water and dried. On recrystallization from ligroin thecompound of formula 4, ##STR23## melting point 106°-107°, is obtained invery good yield.

82.1 Parts of the compound of formula 4 and 79.1 parts of triphenylphosphine in 2000 parts by volume of toluene is boiled for 2 hours withstirring and reflux in the absence of moisture. After cooling, theprecipitate is isolated by filtration with suction and dried. Thecompound of formula 5, ##STR24## is obtained in almost quantitativeyield and is reacted further without additional purification.

53.2 Parts of the compound of formula 5 are dissolved in 4000 parts ofwater with heating and stirring. A solution of 21.3 parts of sodiumperiodate in 200 parts of water is added rapidly and stirring continuedfor 10 minutes. After cooling, the precipitate is filtered with suctionand dried. The compound of formula 6, ##STR25## is obtained in very goodyield.

To a mixture of 75 parts of the compound of formula 6 in 900 parts byvolume of absolute ethyl alcohol, a solution of 9.8 parts of sodiumethylate in 290 parts by volume of absolute ethyl alcohol is slowlyadded at 60° with stirring. The mixture is held at the refluxingtemperature for 3 hours, after which it is cooled and the precipitatefiltered with suction, washed with water, dried and recrystallized fromchlorobenzene with the addition of bleaching earth. The compound offormula 1, melting point 252°-255°, is obtained.

Method β

A clear solution of 26.7 parts of the phosphonium salt of formula 5 in600 parts of dimethyl formamide is raised to 60°-65°. A freshly preparedsolution of 1.5 parts of sodium in 30 parts of methyl alcohol is addedin 15 minutes under nitrogen in the absence of moisture. The deeporange-red suspension is stirred for 30 minutes at 80° and thenevaporated to dryness in a water-jet vacuum at 50°. The residue isstirred into 200 parts of xylene to give a suspension which is heated to100°-110°. In the course of 2 hours a warm solution of 3.3 parts ofsulphur in 130 parts of xylene is added dropwise. The suspension isstirred for 2 hours at 120°-125° until completely decolourized and thencooled. The precipitate is isolated by filtration with suction, washedwith methyl alcohol and then with water, dried and recrystallized fromtrichlorobenzene with the addition of a small amount of bleaching earth.The compound of formula 1, melting point 253°-256°, is obtained in theform of pale yellow crystals.

Method γ

The compound of formula 1 is also obtainable by reacting a solution of26.7 parts of the phosphonium salt of formula 5 in 600 parts of drydimethyl formamide with 10.5 parts of 4-cyano-4'-biphenyl aldehyde inthe presence of 3 parts of sodium methylate at 70°-80° under nitrogen.

The 4-cyano-4'-biphenyl aldehyde, melting point 157°-158°, can beobtained in high yield by the hydrolysis of the urotropine salt of4-cyano-4'-(bromomethyl)-diphenyl [formula 4] in boiling aqueous aceticacid (the Sommelet reaction).

Method δ

Over about 30 minutes a solution of 27.2 parts of4-(bromomethyl)-4'-cyanobiphenyl [formula 4] in 300 parts of dry xyleneis added dropwise 20 parts of triethyl phosphite. On completion of theaddition the xylene and the ethyl bromide formed in the reaction aredistilled off in a column. The clear solution is held for 14 hours at190°. After cooling to 60° the excess triethyl phosphite is removed inhigh vacuum at 0.01 mm. The crude diethyl phosphonate (31.2 parts) isset with 320 parts of dimethyl formamide and 21 parts of4-cyano-4'-diphenyl aldehyde under nitrogen in the absence of moistureand raised to about 40°. A clear solution forms, into which a freshlyprepared solution of 2.6 parts of sodium in 30 parts of methyl alcoholis dropped in 15 minutes. On completion of the addition the brown-yellowsuspension is stirred further for 30 minutes at 40° and then for 3 hoursat 80°. After cooling the reaction mixture is diluted with 640 parts ofmethyl alcohol and the precipitate is filtered with suction, washed withwater, dried and recrystallized from dimethyl formamide ortrichlorobenzene. The compound of formula 1 is obtained in analyticallypure state. It melts at 253°-256°.

Method ε

A mixture of 24.5 parts of p,p'-bis-(4-bromophenyl)-stilbene and 13.4parts of copper (I) cyanide in 200 parts by volume of quinoline isreacted for 16 hours with reflux. After cooling a dark brown slurry isobtained, which is filtered with suction. The filter cake is treatedsuccessively with about 100 parts by volume each of cold concentratedhydrochloric acid, water, concentrated ammonia, water and finallyacetone, after which it is dried. A pale brown powder is obtained whichis dissolved in 2000 parts by volume of 1,2,4-trichlorobenzene, with thesubsequent addition of a few parts of bleaching earth. The mixture isboiled for 10 to 20 minutes with reflux and filtered hot. The hotsolution can be clarified further by boiling for a short time with a fewparts by weight of basic aluminum oxide, activity stage II, followed byhot filtration. After cooling the precipitated substance is isolated byfiltration with suction in the form of long spear-shaped, pale yellowneedles, washed with cold methanol and vacuum dried. Approximately 16parts by weight (80% of theory) of the crude product are obtained. Afterfurther recrystallization (twice from trichlorobenzene or dimethylformamide) a pale yellow compound conforming to formula 1, melting point252°-255°, is obtained in good yield. The solution of this compound in1,2,4-trichlorobenzene is colourless, fluoresces intensely with a violetcolour and in ultra-violet radiation has its absorption maximumwavelength at 360-363 nm (extinction: 6.10⁴).

The p,p'-bis-(4-bromophenyl)-stilbene of formula 7, ##STR26## used asstarting material can be produced, for example, by the followingmethods.

In the absence of moisture and atmospheric oxygen, 13.1 parts oftriphenyl phosphine are added at 60°-65° to a solution of 16.3 parts of4-bromo-4'-(bromomethyl)-biphenyl in 400 parts of dimethyl formamide.Stirring is continued for 3 hours at 80°, then the clear, colourlesssolution is adjusted to 60° again and in 15 minutes a freshly preparedsolution of 1.3 parts of sodium in 25 parts of methyl alcohol is addeddropwise. The deep orange-red suspension is stirred for a further 30minutes and then evaporated to dryness in a water-jet vacuum at 50°. Theresidue is stirred into 200 parts of xylene, the suspension raised to100°-110° and a warm solution of 3.3 parts of sulphur in 130 parts ofxylene added dropwise in 2 hours. Stirring is continued for 2 hours at120°-125° for complete decolourization. After cooling to roomtemperature the yellow precipitate is filtered with suction, washed withmethyl alcohol and water and dried. The compound of formula 7 isobtained in good yield with melting point 346°-352° and is sufficientlypure for further reaction. It can be purified by recrystallization from1,2,4-trichlorobenzene with the addition of a small amount of bleachingearth, on which it is obtained in the form of pale yellow needles withmelting point 356°-358°.

The 4-bromo-4'-(bromomethyl)-biphenyl, melting point 92°-94°, can beproduced, for example, by side-chain bromination of 4-bromo-4'-methylbiphenyl [formula 2] in chlorobenzene with ultra-violet irradiation.

The solution of the phosphonium salt in 400 parts of dimethyl formamideobtained from 16.3 parts of 4-bromo-4'-(bromomethyl)-biphenyl and 13.1parts of triphenyl phosphine (see above), when reacted with 13.1 partsof 4-bromo-4'-biphenylaldehyde in the presence of 3 parts of sodiummethylate at 70°-80°, also gives the compound of formula 7 in good yieldin the form of a pale yellow powder with melting point 348°-356°.

The 4-bromo-4'-diphenylaldehyde, melting point 137°-140°, can beproduced in a simple manner by hydrolysis of the urotropine salt of4-bromo-4'-(bromomethyl)-biphenyl in boiling aqueous acetic acidsolution (the Sommelet reaction).

Treatment of a 20% solution of the fumaric acidbis-(4'-bromodiphenyl-4-)ester of formula 8, ##STR27## in boilingDowtherm A (a mixture of approximately 78% diphenyl ether and 22%diphenyl) for 50 hours under nitrogen, purification of the cold filteredcrude product by treatment with a little boiling dimethyl formamide fora short time and recrystallization of the hot filtered residue from1,2,4-trichlorobenzene using some bleaching earth results in thecompound of formula 7 in the form of pale yellow crystals. It isanalytically pure and melts at 356°-358°.

The fumaric acid diaryl ester of formula 8 can be effectively producedby treating a solution of 2 mols of 4'-bromo-4-hydroxy-diphenyl (lit.melting point 164°-166° ) and 1 mol of fumaric acid dichloride ino-dichlorobenzene for 2 hours at 150° and for a further 4 hours at therefluxing temperature, cooling, isolation by filtration with suction andrecrystallization from chlorobenzene using bleaching earth. Yellowneedles, melting point 256°-259°, are obtained, which are sufficientlypure for further reaction.

The stilbene compound of formula 7 can be produced from 2 mols of4'-bromodiphenyl aldehyde-4 by benzoine condensation, subsequentreduction to the corresponding desoxybenzoine with simultaneous thermaltreatment with aluminium isopropylate according to G. Drefahl and K.Thalmann, J. prakt. Chemie, 4th series, 20, 60 (1963), by using in placeof p-terphenyl aldehyde-4 the equivalent amount of 4'-bromo-diphenylaldehyde-4, on which intermediates of the following formulae areobtained, ##STR28## or by reaction of 2 mols of 4'-bromodiphenylaldehyde-4 with 1 mol of hydrazine to the aldazine of formula, ##STR29##and thermal treatment of this compound in Dowtherm A under the samereaction conditions as in the thermal treatment of the fumaric acidester of formula 8, (cf. Bull. Soc. Chim. France 1970, 2, pp. 525-527),or by cleavage of hydrogen bromide, with simultaneous rearrangement,from the compound of formula 13, ##STR30## in boiling ethylene glycol[H. Sieber, Liebigs Ann. Chem. 730, 31-46, 1969] or in amyl alcohol[Al-Attar and R. Wizinger, Helv. Chim. Acta 46, 1286, 1963; the1,1-diaryl-2-bromomethane of formula 13 is accessible from4-bromodiphenyl and bromacetaldehyde]; or by dehalogenation of thecompound of formula 14, ##STR31## with reducing metals, e.g. zinc, orcopper (I) compounds (Soc. 1943, 1:, Referat C. 1943 II, 715) ortriphenyl phosphine (J. Org. Chem. 36, 2377-79, 1971).

If the compound of formula 14 is reacted with excess copper (I) cyanideunder suitable conditions, the two bromine atoms bound to the benzenenuclei are removed and replaced by cyano groups. The compound of formula(1) is then obtained directly (method ε bis).

Method θ

23.5 Parts by weight of fumaric acid bis-(4'-cyanodiphenyl-4)-ester offormula 15, ##STR32## are dissolved in 70 parts by volume of Dowtherm A(a mixture of about 78% diphenyl ether and about 22% diphenyl) withheating. The solution is reacted for 50 hours at about 250° undernitrogen with reflux. After cooling the crystallized crude product isrecrystallized in the same way as in method α. The compound obtained hasthe formula 1 and shows the properties given in method (a).

The fumaric acid ester of formula 15 is produced analogously to thereaction of 4'-bromo-4-hydroxydiphenyl to the fumaric acid ester offormula 8 from 4'-cyano-4-hydroxydiphenyl (production from the brominederivative by reaction with CuCN in dimethyl formamide) and fumaric acidchloride with recrystallization from benzene using bleaching earth. Apowder of beige colour, melting point 260°-270°, is obtained which issufficiently pure for further reaction.

EXAMPLE 2

Production of the compound of formula 16, ##STR33## 18.9 Parts of thecompound of formula 17, ##STR34## 30 parts of p-terphenyl aldehyde anileand 20.1 parts of potassium tert. butylate are entered into 960 parts byvolume of dimethyl formamide. The solution is raised to 90° in 30minutes under a nitrogen atmosphere with stirring and held at 90°-95°for 1 hour with continued stirring. After cooling the reaction mixtureto 10°-20°, 630 parts of water and then 540 parts by volume of 10%hydrochloric acid are added. The precipitate is filtered with suction,washed with water and dried. After recrystallization fromo-dichlorobenzene with the addition of bleaching earth the compound offormula 16, melting point > 350°, is obtained in good yield. Itfluoresces blue-violet in trichlorobenzene solution and the absorptionmaximum wavelength in this solvent is at 375 nm.

EXAMPLE 3

If the procedure of Example 2 is carried out using, in place of 18.9parts of the compound of formula 17, 24 parts of the compound of formula18, ##STR35## the compound of formula 19, ##STR36## is obtained in goodyield. On purification from dimethyl formamide it is obtained as a paleyellow powder with melting point 133° and absorption maximum wavelengthat 379 nm in trichlorobenzene solution.

EXAMPLE 4

Production of the compound of formula 20, ##STR37## 31.4 Parts of thecompound of formula 21, ##STR38## and 28 parts of triphenyl phosphineare added to 500 parts by volume of dimethyl formamide and reacted for 3hours at 80° with sti-ring. After this time 26 parts of p-terphenylaldehyde are added to the clear solution, followed by 11 parts of sodiummethylate. The mixture is stirred further for 3 hours at 80° and thencooled to 10°-20°. The precipitate is filtered with suction, dried andrecrystallized from chlorobenzene with the addition of bleaching earth.The compound of formula 20 is obtained in good yield with melting point320° and an absorption maximum wavelength in trichlorobenzene at 363 nm.

The compound of formula 21 can be produced as follows.

11.3 Parts of sodium are dissolved in 200 parts of absolute ethylalcohol with stirring. At room temperature 57.2 parts of iso-amylnitrite are slowly added. The mixture is cooled to 0°-5° and at thistemperature 65.7 parts of 4-methyl acetophenone are gradually addeddropwise. The mixture is stirred for 24 hours at 0°-5° and then for afurther 24 hours at room temperature. The precipitate is isolated byfiltration with suction, washed thoroughly with ether and dried. It isdissolved in 800 parts of ice-water, the solution decolourized withactivated carbon and then set slowly with 80 parts of glacial aceticacid with vigorous stirring. A white precipitate forms which is filteredwith suction, washed until neutral and dried. The compound of formula22, ##STR39## melting point 108°-109°, is obtained in good yield and isreacted further without additional purification.

20.8 Parts of the compound of formula 22 are dissolved in 185 parts ofmethanol and a solution of 2.7 parts of glacial acetic acid in 2.7 partsof water is added to the solution. 13.7 Parts of phenyl hydrazine areslowly added dropwise and stirring continued for a further hour. Thereaction mixture is fully evaporated in vacuum and the dry crude productsuspended in 116 parts of glacial acetic acid. The suspension isgradually added to 250 parts of melted urea at 150° with stirring.Stirring is continued for 3 hours at 175°, then the mixture is cooled to140° and 400 parts of 2 N sodium hydroxide solution are gradually added.The reaction mixture is finally cooled to 0°-5° and the precipitatefiltered with suction, washed neutral with water and dried. Aftercrystallization from petroleum ether the compound of formula 23,##STR40## is obtained with melting point 66°-68°.

A solution of 20 parts of the compound of formula 23, 15.2 parts ofN-bromosuccinimide and 0.2 parts of benzoyl peroxide in 85 parts byvolume of carbon tetrachloride is reacted for 6 hours with stirring andreflux. After cooling the precipitate is filtered with suction and thefiltrate heavily evaporated with vacuum, on which the compound offormula 21 settles out. On purification from ligroin it has a meltingpoint of 121°-122°. The crude product is however sufficiently pure forthe next reaction.

EXAMPLE 5

Production of the compound of formula 24, ##STR41##

If the procedure of Example 4 is carried out using in place of 31.4parts of the compound of formula 21, 35.3 parts of the compound offormula 25, ##STR42## the compound of formula 24 is obtained in goodyield. After purification from dimethyl formamide with the aid ofdecolourizing carbon its melting point is 267°-268° and the absorptionmaximum wavelength in trichlorobenzene at 370 nm.

The compound of formula 25 can be produced as follows. 100 Parts of3-cyano-4-methyl-1-aminobenzene (prepared from the corresponding nitrocompound by reduction according to Bechamp) are dissolved in 320 partsby volume of glacial acetic acid. The solution is dropped into a mixtureof 42 parts by volume of sulphuric acid and 610 parts of ice in 30minutes, after which a solution of 54 parts of sodium nitrite in 114parts of water is added dropwise. The resulting diazo solution isstirred for a further 30 minutes.

A solution of 9.9 parts of sodium sulphite in 76 parts of water is addedto 70 parts of isonitrosoacetone in 760 parts of water, followed by asolution of 19 parts of copper sulphate in 76 parts of water. Aftercooling to 0° the diazo solution is added. The mixture is allowed tostand for 12 hours, after which the precipitate is filtered with sucton,washed with water and dried. On recrystallization from ligroin thecompound of formula 26, ##STR43## melting point 185°-186°, is obtainedin good yield.

A hot solution of 71.3 parts of the compound of formula 26 in 1060 partsby volume of methanol is set with 151.2 parts by volume of acetic acid1:1. The mixture is held at the boil for a short time, then 38.1 partsof phenyl hydrazine are added slowly. The suspension is boiled for afurther 2 hours with reflux and cooled, and the precipitate filteredwith suction and dried. The compound of formula 27, ##STR44## meltingpoint 248° (crystallization from chlorobenzene), is obtained in verygood yield.

300 Parts by volume of acetic anhydride and 200 parts by volume ofpyridine are added to 73 parts of the compound of formula 27 in 275parts by volume of dimethyl formamide. The mixture is raised to 80° in 1hour 30 minutes, held at this temperature for 2 hours and then at 100°for 4 hours, after which it is raised to the boiling temperature andboiled for 30 minutes with reflux. After cooling the reaction mixture isrun into 2000 parts of water, the precipitate filtered with suction,dried and recrystallized from methanol. The compound of formula 28,##STR45## melting point 141°-142°, is obtained in very good yield.

The compound of formula 28 is reacted further with N-bromosuccimide tothe compound of formula 25 in analogy with the method given for thecompound of formula 23. On purification from ligroin the compound offormula 25 has a melting point of 147°-148°.

EXAMPLE 6

Production of the compound of formula 29, ##STR46## 20 Parts of thecompound of formula 30, ##STR47## and 15.3 parts of triphenyl phosphineare dissolved in 480 parts by volume of dimethyl formamide. The solutionis held for 3 hours at 80° under a nitrogen atmosphere with stirring.The clear solution is then set with 12.4 parts of the compound offormula 31, ##STR48## and 6 parts of sodium methylate, and then heatedfurther for 4 hours at 80°. After cooling the precipitate is filteredwith suction, washed with water and dried. On recrystallization fromchlorobenzene with the addition of bleaching earth, the compound offormula 29 is obtained in good yield. Its melting point is above 350°and the absorption maximum wavelength in dimethyl sulphoxide is at 375nm.

The compound of formula 30 can be formed from the compound of formula32, ##STR49## by bromination with N-bromosuccinimide in analogy with themethod given for the compound of formula 23. On recrystallization fromchlorobenzene its melting point is 195°-197°.

The compound of formula 32 can be produced as follows. ##STR50## and19.4 parts of o-aminophenol in solution in 284 parts of polyphosphoricacid are raised to 110° with stirring under a nitrogen atmosphere, heldat this temperature for 10 minutes, then heated further to 210° andstirred for 3 hours at 210°-220°. The temperature is allowed to fall toabout 100° and the mixture unloaded into 1400 parts of ice-water. Theprecipitate is filtered with suction, washed with 10% soda solution andthen with water until neutral, and dried. The compound of formula 32 isobtained in almost quantitative yield and is used further withoutadditional purification. After recrystallization from ethanol themelting point of the compound of formula 32 is 169°-170°.

The compound of formula 31 can be produced as follows. A mixture of 20parts of the compound of formula ##STR51## in 500 parts of chlorobenzeneis raised to the boiling temperature with stirring and set slowly, withsimultaneous ultra-violet irradiation, with a solution of 15.3 parts ofbromine in 100 parts of chlorobenzene. Stirring and irradiation arecontinued at boiling temperature until the evolution of hydrogen bromideabates (5-6 hours). The mixture is cooled and the precipitate filteredwith suction, washed with cold chlorobenzene and dried. The compound offormula 35, ##STR52## is obtained in very good yield. On purificationfrom chlorobenzene its melting point is 168°-169°.

The compound of formula 31 is finally obtained from the compound offormula 35 by the Sommelet reaction; its melting point is 160°-161°.

EXAMPLE 7

Production of the compound of formula 36, ##STR53##

In analogy with the procedure of Example 1, the compound of formula 30is converted by reaction with triphenyl phosphine and exchange of thebromine anion for the periodate anion into the compound of formula 37,##STR54## which is reacted with sodium ethylate to yield the compound offormula 36. On purification from dimethyo formamide, the compound offormula 36 has a melting point above 350°; the absorption maximumwavelength in trichlorobenzene solution is at 372 nm.

EXAMPLE 8

Production of the compound of formula 38, ##STR55##

In analogy with the procedures of Examples 1 and 7, from the compound offormula 39, ##STR56## is produced the compound of formula 38; itsmelting point is above 350° and the absorption maximum wavelength intrichlorobenzene is at 375 nm.

The compound of formula 39 can be obtained from the compound of formula40, ##STR57## in analogy with the method given for the compound offormula 23. After recrystallization from ethanol its melting point is205°-206°. The compound of formula 40 can be produced as follows.

A mixture of 16.5 parts of 2-hydroxy-5-tert.butyl-1-aminobenzene, 21.2parts of the compound of formula 33, 2 parts of boric acid and 8.5 partsof piperidine in 140 parts by volume of 1,2,4-trichlorobenzene is raisedto 160° in 1 hour with stirring under a nitrogen atmosphere, held at160°-170° for 1 hour and then heated further to 200° in 1 hour. Themixture is stirred at 210° for 1 hour and finally held at boilingtemperature for 4 hours with reflux. The water formed in the reaction isazeotropically removed. After cooling, 70 parts by volume of isopropylalcohol are added to the reaction mixture. Stirring is continued for 30minutes, then the precipitate is filtered with suction and dried. It isrecrystallized from ethanol, on which the compound of formula 40 isobtained in very good yield with melting point 167°-168°.

EXAMPLE 9

In analogy with the operating procedures of Examples 1 and 7 thecompound of formula 41, ##STR58## is reacted to yield the compound offormula 42, ##STR59##

The compound of formula 41 can be formed from the starting compound offormula 43, ##STR60## in accordance with the mode of operation given forthe compounds of formulae 22, 23 and 21.

EXAMPLE 10

In analogy with the procedures described in Examples 1 and 7 thecompound of formula 44, ##STR61## (melting point 223°) is employed toyield the compound of formula 45, ##STR62## the melting point of whichis above 360° and the absorption maximum wavelength in CHCl₃ at 382 nm.The compound of formula 44 can be produced by bromination of thecorresponding methyl compound (melting point 215°-216°), which in itsturn can be obtained from the compound of formula 33 in analogy with themethod described in Helv. Chim. Acta 50, 955 (1967).

EXAMPLE 11

In analogy with the procedure of Example 5, the compound of formula 46,##STR63## (melting point 300°-302°) can be produced from2,4-dicyanobenzyl bromide and diphenyl aldehyde. The 2,4-dicyanobenzylbromide (melting point 106°) can be obtained by bromination of2,4-dicyanotoluene (melting point 142°-143°) with bromine inchlorobenzene with ultra-violet irradiation. The 2,4-dicyanotoluene canbe formed from 3-cyano-4-methyl-1-aminobenzene by the Sandmeyerreaction.

EXAMPLE 12

In full analogy with the operating procedure yielding the compound offormula 24, the compound of formula 47, ##STR64## is produced from thecompound of formula 25 and diphenyl aldehyde. On recrystallization from"Cellosolve" its melting point is 245°-246°. The absorption maximumwavelength in CHCl₃ is at 360 nm, the emission maximum in CHCl₃ at 433nm.

EXAMPLE 13

If the procedure of Example 1, method θ is adopted, with the 23.5 partsof fumaric acid bis-(4'-cyanodiphenyl-4)-ester of formula 15 replaced by28.2 parts of the fumaric acid ester of formula 48, ##STR65## afterrepeated recrystallization from 1,2,4-trichlorobenzene with the additionof bleaching earth, a yellow-green powder is obtained which did not meltat 350°.

This compound, which is obtained in the analytically pure state, agreeswith the formula 49, ##STR66##

The solution of this compound in 1,2,4-trichlorobenzene is colourless,shows intense red-violet fluorescence and has its absorption maximumwavelength in ultra-violet radiation at 361 nm (extinction maximum5.6×10⁴).

The fumaric acid ester of formula 48 can be derived from4'-hydroxydiphenyl-4-carboxylic acid ethylester (accessible from4'-cyano-4-hydroxydiphenyl by alcoholysis with ethyl alcohol andsulphuric acid) and fumaric acid dichloride in the same way as thefumaric acid esters of formulae 8 and 15. Subsequent purification byrecrystallization from chlorobenzene with the aid of bleaching earthresults in a yellow crystalline powder which melts at 259°-267° and issufficiently pure for further use.

EXAMPLE 14

In analogy with the procedure of Example 1, the compound of formula 50,##STR67## is reacted to yield the compound of formula 51, ##STR68##

The compound of formula 50 can be produced by bromination of thecorresponding methyl compound of formula 52, ##STR69## which in turn canbe obtained from methyl-1,1'-diphenyl-4'-sulphonic acid (obtainable inaccordance with Ber. 65, (1932), pp. 1382-87) in analogy with the methodgiven in J. Chem. Soc. London 1960, II, p. 2508. Solutions of thecompound of formula 51 in o-dichlorobenzene display intense blue-violetfluorescence.

EXAMPLE 15

In analogy with the procedure of Example 5, the compound of formula 25and an equivalent amount of the compound of formula 53, ##STR70## can beemployed as starting materials to yield the compound of formula 54,##STR71##

In chlorobenzene solution the latter compound fluoresces blue-violet.The compound of formula 53 can be obtained, for example, by working inaccordance with the teaching of U.S. Pat. No. 2,280,504 (cf. Belstein E.III 7³, 2091).

EXAMPLE 16

If the procedure of Example 1, method ε is employed with the 24.5 partsof the compound of formula 7 replaced by 26 parts of the compound offormula 55, ##STR72## a pale yellow compound with the formula 56,##STR73## is obtained, which shows violet fluorescence intrichlorobenzene solution.

The compound of formula 55 can be obtained, for example, by reaction ofthe compound of formula 57, ##STR74## with the stoichiometric amount oftriphenyl phosphine, with simultaneous exchange of the bromine anion bythe periodate anion, to give the compound of formula 58, ##STR75## whichis reacted with sodium ethylate in analogy with Example 7. The startingcompound of formula 57 is formed by reacting 3-methyl-4-bromodiphenyl(Bp₇₆₀ 318°-323°; Bp.₃ 165°-170°; n_(D) ²⁵ =1,6150; literature:Beilstein E III, Vol. V, p. 1800; J. Am. Chem. Soc. 55 (1933), 1212-1217and 58 (1936), 1249) with excess paraformaldehyde and excess sodiumbromide for 30 hours in a sulphuric acidglacial acetic acid mixture at100°, with subsequent working up by normal methods, on which it isobtained in good yield.

APPLICATION EXAMPLE A

Two parts of the compound of formula 1 are mixed with 2 parts of ahighly sulphonated castor oil, 8 parts of sodium dioctyl phenylpolyglycol ether oxyacetate containing 40 ethenoxy groups in themolecule, and 80 parts of water. The mixture is comminuted in a suitablemachine, for example a sand mill, until the predominant particle sizefraction is of the order of 0.5 to 2 microns.

A bath is prepared with 3000 parts of water, 15 parts of a commercialcarrier, e.g. ortho-dichlorobenzene, and 2 parts of the mixture asabove. At 50° 100 parts of a fabric of polyester (polyethyleneterephthalate) fibre are entered into the bath. The bath is brought tothe boil in 30 minutes and the fabric treated for 45 minutes at the boilwith reflux. On removal the fabric is treated for 10 minutes at 70° andliquor to goods ratio 40:1 in an aqueous solution containing 1.5 g/loctyl phenyl decaglycolether, with subsequent rinsing and drying. Thetreated polyester fabric shows a pronounced optical white effect. If thetreatment is carried out in an enclosed machine at 120°-130°, comparablewhite effects are obtained without the addition of a carrier.

APPLICATION EXAMPLE B

A blend fabric of cotton and a polyester fibre, e.g. polyethyleneterephthalate, is padded at room temperature with a dispersion of 20parts of the brightener mixture formed as in Example A in 1000 parts ofwater. The padding expression leaves the fabric containing 80% of itsweight of the dispersion. After intermediate drying for 30 minutes at60° the fabric is dry heat treated for 1 minute at 200° for fixation.The whiteness value obtained is close to that given by the method ofapplication described in the preceding Application Example. If a fabricof polyester fibre alone is treated ("Dacron", "Terylene", "Diolen"etc.), similar white effects are obtained.

APPLICATION EXAMPLE C

100 Parts of a fabric of polyester fibre, e.g. polyethyleneterephthalate, are treated for 1 hour 30 minutes at 90°-95° in a bathconsisting of 3000 parts of water, 6 parts of 85% formic acid, 6 partsof 80% sodium chlorite, 5 parts of a carrier, e.g. a trichlorobenzenemixture, and 2 parts of the brightener mixture prepared as given inApplication Example A. On removal from the bath the fabric is washedoff, rinsed and dried. It shows a higher whiteness value than acomparable fabric which has been bleached under the same conditions butwithout the addition of the compound of formula 1.

APPLICATION EXAMPLE D

50 Parts of a polyester fabric are entered into a mixture of 250 partsby volume of trichloroethylene and 250 parts by volume of chlorobenzenecontaining in solution 0.2 parts of the compound of formula 1 andtreated for a short time with constant agitation. The excess solvent isremoved by centrifuging to leave the fabric containing roughly its ownweight of the application solution. After vacuum drying a 60°, thefabric is treated for 15 minutes in water vapour at 120° to 130°. Thefabric has an appreciably whiter appearance than a comparable polyesterfabric which has been treated under the same conditions but without abrightener addition.

If in place of polyester fabric a blend fabric of cotton and a polyesterfibre, e.g. "Diolen", is treated by this method, a white effect ofsimilar quality is obtained.

APPLICATION EXAMPLE E

In the feed vessel of a melt spinning machine 200 parts of polyethyleneterephthalate are melted at 280° under nitrogen. 0.04 Parts of thecompound of formula 1 are metered into the melt with stirring. Thebrightener melt at this temperature and is homogeneously distributed inthe polyester as stirring continues. It is followed by 4 parts oftitanium dioxide as delustrant, with further stirring forhomogenization. The melt is extruded through a spinning nozzle and thefilament formed is cooled by a water jet or by air, cold drawn and woundon bobbins.

Products made of the filament have a considerably higher whiteness valuethan comparable products of spun filament containing no incorporatedbrightener.

A comparable white effect is obtained when the compound of formula 45 isused in place of the compound of formula 1.

APPLICATION EXAMPLE F

A mixture of 1000 parts of dimethyl terephthalate, 665 parts of ethyleneglycol, 0.55 parts of manganese acetate, 0.18 parts of antimony trioxideand 0.3 parts of the compound of formula 1 is heated in a reactionvessel of stainless steel fitted with a stirrer and a descending cooler.Splitting off of the methanol begins at about 160° and takes 2 hours 30minutes to complete. Towards the end of this period the temperatureincreases to about 225°. Four parts of titanium dioxide and 0.3 parts ofphosphoric acid are added to the melt, the pressure in the reactionvessel is reduced to below 1 mm and the temperature maintained at 290°until the desired degree of polymerization is reached. The polymer thusproduced is extruded in conventional manner at 2-5 atmospheres excesspressure (inert gas) in the form of filament. The polyester filament hasa high degree of whiteness which is fast to light and washing.

APPLICATION EXAMPLE G

500 Parts of polyamide 6 chips, 1.5 parts of titanium dioxide and 0.1part of the compound of formula 20 are intimately mixed in a mixer andthe mixture charged into the feed vessel of a melt spinning machine,where it is melted at 250°-260° in the absence of oxygen. The melt isextruded with the aid of nitrogen through a spinning nozzle, thefilament cooled, cold drawn to 400% of the initial length, and wound onbobbins. The filament has a high whiteness value. The compounds offormulae 42 or 47 can be employed in place of the compound of formula 20with equally good success.

APPLICATION EXAMPLE H

A melt of 1000 parts of caprolactam containing 30 parts of water and 0.8parts of the brightening agent of formula 20 is reacted with stirringfor 4 hours at 240° under pressure and subsequently for 1 hour with thepressure released. The melt is extruded through a slot die in ribbonform, chilled in water, cut into chips and dried. The dry polyamide 6chips have an appreciably higher degree of whiteness than comparablechips containing no incorporated brightener. The compound of formula 1may be employed in equivalent manner.

APPLICATION EXAMPLE J

A batch of polypropylene granules delustred with titanium dioxide ispowdered in a mixer with 0.01 to 0.05% of its weight of the compond offormula 16. The granules are loaded into a melt spinning machine, meltedat 310° under nitrogen and spun in filament form. The filament is hotdrawn by the two-stage process. It shows an appreciably higher degree ofwhiteness than comparable filament containing no brightener.

Similar white effects can be obtained in this method of application withthe compounds of formulae 19 and 20 in place of the compound of formula16.

APPLICATION EXAMPLE K

A solution of 200 parts of polyvinyl chloride and 0.04 parts of thecompound of formula 1 in methylene chloride is converted into filamentby the wet spinning process. A brilliant white filament is obtainedwhich has good light fastness. For this application the compounds offormulae 46 and 24 are equally as suitable as that of formula 1.

APPLICATION EXAMPLE L

200 Parts of polypropylene granules are powdered in a mixer with 0.04parts of the compound of formula 19. After processing on a three-rollmill at 140° to 220°, the mixture is either moulded in the form ofpanels or regranulated and injection moulded in the desired form. Themoulded products have a distinctly higher degree of whiteness thancomparable products without a brightener additive.

If the compound of formula 17 or 38 is used in place of that of formula19, similar white effects are obtained.

APPLICATION EXAMPLE M

100 Parts of polyester granules are powdered in a mixer with 0.02 partsof the compound of formula 1 and injection moulded. The moulded productsare of superior appearance to products containing no incorporatedbrightener. In this Example the polyester granules can be replaced byother granulated materials, for example polyamide, polystyrene,polyethylene or cellulose acetate, on which white effects of similarquality are obtained; the same applies when the compound of formula 1 isreplaced by the compound of formula 45.

APPLICATION EXAMPLE N

An amount of 0.01 to 0.05 parts of the compound of formula 20 is mixedwith 100 parts of moulding material consisting of 65 parts of polyvinylchloride, 35 parts of a plasticizer, e.g. dioctyl phthalate, and 2%,relative to the polymer, of a stabilizer. The mixture is processed on amulti-roll mill for 3 to 6 minutes at 165° to 185°, transferred to anextrusion moulding machine and extruded as film. If opaque film isdesired, 2.5% titanium dioxide is incorporated in the mixture prior toprocessing.

The films are superior in appearance to films produced without abrightener additive.

APPLICATION EXAMPLE O

A mixture of 2 parts of the compound of formula 1,2 parts of a highlysulphonated castor oil, 8 parts of sodium dioctyl phenyl polyglycoletheroxy acetate containing 40 ethenoxy groups in the molecule and 80parts of water is prepared. The mixture is ground in a suitable machinesuch as a sand mill until the major fraction of the particles is withinthe size range 0.5 to 2 microns.

20 Parts of the resulting dispersion, are dispersed in 1000 parts ofwater. The liquor is padded on a fabric of polyester fibre, e.g.polyethylene terephthalate, at room temperature and at an expressionleaving the fabric with 80% of its weight of the liquor. The fabric isdried for 30 minutes at 60° and treated for 1 minute in dry heat at 220°for fixation. The fabric is strongly brightened.

This method of application can also be employed for the opticalbrightening of blend fabrics of 67 parts of polyethylene terephthalateand 33 parts of cotton, or of fabrics of polyester fibre of differentcomposition, e.g. 1-4-dimethylocyclohexane terephthalate.

What we claim is:
 1. A compound of the formula, ##STR76## in which R₁and R₅ each signifies hydrogen or linear alkyl of 1 to 4 carbonatoms,R₂, R₃, R₄, R₆, R₇ and R₈ each signifies hydrogen, halogen, alkylor alkoxy of 1 to 8 carbon atoms, alkenyl of 3 to 8 carbon atoms, or-COOR',in which R' signifies hydrogen, alkyl of 1 to 22 carbon atoms,hydroxyalkyl of 2 to 4 carbon atoms, phenyl or methyl- orchlorine-substituted phenyl, p signifies an integer from 1 to 3, and qsignifies an integer from 1 to 3, provided that the total of p and q is4, 5 or 6, at least one of R₃ and R₇ being -COOR'.
 2. A compound offormula I, according to claim 1, in which R₁ and R₅ each signifieshydrogen or methyl; and R₂, R₃, R₄, R₆, R₇ and R₈ each signifieshydrogen, fluorine, chlorine, methyl, methoxy, alkenyl of 2 to 4 carbonatoms, carboxyl or carboxylic acid alkyl (C₁₋₁₄) ester.
 3. A compoundaccording to claim 1, in which R₂, R₄, R₆ and R₈ signify hydrogen.
 4. Acompound according to claim 1 wherein R₁ and R₅ are hydrogen.
 5. Acompound according to claim 4 of the formula, ##STR77##